Deposition

The capacity to deposit different materials is clearly one of the qualifying aspects of an advanced front-end structure. In our case we use four different pieces of equipment for dielectric materials and one for metals.

Dielectric Materials

Specifically for dielectric materials we have:

STS MAC

This system is designed to deposit dielectric material with high accuracy refractive index (RI) and elevate absorption coefficient control. It is configured with 2 different plasma sources at different frequencies (380KHz and 13.56MHz), dedicated to control both stress and deposition rate.

The control of RI is achieved by doping the layer with controlled GeH4 flow or a proper mixture gas reactions between SiH4 /NH3 /N20 gases in a process reactor at 350 °C and MTorr pressure range. The system is equipped with an automatic loading robot and vacuum transfer cham- ber for high throughput.

OXFORD PLUS PRO 100

This equipment deposits planarized dielectric materials with and conformal coating.

It uses PECVD plasma system under vacuum and controlled temperature from liquid precursors (TMB TMP and TEOS). The deposited layer is processed to have low flow temperature in order to achieve high conformal properties on topographies with high aspect ratio.

SEMCO system and VTR 7000

These systems are utilized for the deposition of dielectric materials with stoichiometric compositions (Si3N4) and Polysilicon, using Low Pressure Chemical Vapour Deposition (LPCVD).

The Semco system is also equipped for annealing and oxidation: such processes are in fact complementary for the material consolidation after Plasma depositions and are also used to grow stoichiometric oxide layers on Silicon surfaces.

Metals

The deposition of metal films is necessary to implement the following features on the devices: adhesion layers, barrier layers, electrical contacts, resistors and alloys. Such technology prepares the device for the following packaging interconnection and soldering. The equipment dedicated to this purpose is the:

TEMESCAL BCD2800 evaporation system, configured with six crucibles, one process chamber and a Cryo pump system. It is also equipped with six “crystal control systems” and the total process length is 1m in order to optimize the depositions by “Lift-off “ technique.

The configuration of the tool can guarantee any sequence deposition for high thickness as well as an accurate control of stoichiometric alloys (for example Au/Sn 80/20 weight %).